Virtual property is an interesting subject, because it causes problems that real property doesn't have. One of these problems is the perennity of virtual items you buy. If you buy a sparkly pony in World of Warcraft from Blizzard, you expect that mount to be around for a while. At least as long as you still want to play that game. But what happens if Blizzard decides that they want to shut down WoW? If you only pay subscriptions, you can't really complain if a game company says that they'll stop accepting subscription payments and will close down a game in 6 months (like SOE did with Star Wars Galaxies). But if the business model is Free2Play with an item shop, a game closing down effectively makes the items you bought in that shop disappear, which obviously leads to upset customers.
This is exactly the problem Google has at the moment. They bought a social apps company named Slide a year ago for $200 million, and now decided to shut it down, probably because they started their own social network Google+ now. But Slide had a Free2Play casual game called SuperPoke! Pets, and according to the Washington Post the players are threatening law suits because of the money they "invested" in that game. In some cases thousands of dollars.
Now players in general tend to get rather upset if they can't access their online games. I recently started playing The Sims Social, which is a nice version of The Sims for Facebook. And although I didn't invest any money in it, I'm annoyed that I can't access that game due to a bug which affects many players and which gets you stuck on the loading screen at 65%. But in that situation I obviously have no legal case, and anyway it probably is just a temporary inconvenience. In the case of Star Wars Galaxies I did pay money for a subscription a long time ago, but as I haven't played for years I'm not really bothered, and I don't consider the time and money spent as an "investment".
A game I am currently playing, and where I bought something from the item shop, is World of Tanks. Now WoT is doing great, and I don't expect them to shut down anytime soon. But I do admit that I never read the legalese text that undoubtedly exists somewhere telling me what exactly my property rights are on the Löwe tank I paid real money for. Presumably I clicked through a legal agreement telling me that I don't have any rights at all. And so did the players of SuperPoke! Pets. But the legality of click-through agreements is not yet universally accepted, although US courts tend to consider them legal. And in the case of virtual property it isn't quite clear whether certain laws about property rights or consumer protection don't override the license terms. So unless the SuperPoke! Pets players really sue Google and thus establish some precedence, it is very hard to say what your virtual property rights are. In China there have been several cases where courts considered that the buyers had some fundamental rights even with virtual property they bought.
I'd like to hear from you whether there are games in which you feel invested to a point where you would consider a law suit if the game and your virtual property was taken away from you. Do you accept that you have absolutely no rights at all? Or do you consider that the time and money you spent on an online game under certain conditions gives you certain rights, even if you clicked accept on some terms of service you never read?